Idle port



April 7, 1936. H. A. BOLLER IDLE PORT Filed July 19, 1934 IFIG.|

FIG.2

HENRY A. BOLLER INVEN TOR.

A TTORNEY.

Patented Aph 711936 cnry A. Boiler, Benoit, Mich, assignor her warburetor Corporation, St. o... a cor poration of hell.

p ut nmry it. i934, Sci no. "name solar. iUl. ear-tn This invention relates to carburetors and are particularly to improvements in the construction and formation of the idle or low speed iuel supply device of plain tube carburetors.

Prior to this invention it has been custoary to form a slit in the wall oi the carburetor at a point adjacent the throttle valve when it is in closed position so that the slit will ve one portion exposed to the suction conditions in the m mixing conduit anterior to the throttle when it is closed and in most cases at least a small portion of the slit will be posterior to the throttle. It is desirable for the slit to have substantial length so as to get a gradual variation of the application of suction to the slit as the throttle is opened and since the manlmumpermissible capacity of the slit is lowit must be made very narrow. It will be understood that such idle discharge passages are fed with fuel'and serve to supply the requirements of the engine during low speed operation.

That portion of the carburetor body in which the low speed discharge passageway and the outlet of the mixing conduit are formed is preierably made of cast iron, and no satisfactory method of forming long narrow slits suitable. for idle discharge passages in these cast iron bodies has been found. The best previous method of forming I these. passages has involved a punching operation which is not satisfactory in cast ironbecause the line of shear or breakage cannot be held toexact shapes or sizes. The result is that there is a verysubstantial variation in the flow resisting ellcc'tof passages formed by this method and the richthree miles-per gallon at low speeds. The nature of the variation is frequently such that cannot be corrected by an idle adjustment screw.

. It is an object of this invention to provide a new and improved idle construction which can be made to exact specifications in quantity production without danger of such breakages in the metal and variations in the shape and. size of the idle discharge passages as to pause undue 45 richness or leanness of the carburetor at low speeds. I

I The invention will be better understood upon reference to the accompanying drawing in which Figure -1 is a schematic representation of a car- 50 buretor having my invention applied thereto.

Figure 2 is a detailed view taken along the lines 2-'-2of Figure 1 with the idle adjusting screw removed and on an enlarged scale.

. Referring to the drawing the reference numeral 55 l indicates the main body member of a carburetor the openlng l8.

ness of the idle mixture mayyary asmuch as trimmed with a passageway t which is in efiect a continuation of the main air inlet. Venturis generally indicated by the reference numeral llead to the mixing chamber t and the outlet oi. the carburetor which is controlled by throttle valve 9 rotatably mounted on the shaft it. llhe air inlet is controlled by the choice valve. ll rotatably mounted on shaft it, and fuel is supplied to the ven'turis by means oi a main nozzle it. This much of the structure is conventional and may be varied substially without edecting the nature and operation of the improved idle construction which will now be described.

- A downwardly conducting idle passageway it is formed in a wall oi the carburetor; this pas- 20 sageway has an inlet it which is supplied with fuel such as gasoline from any suitable source such for instance asthe constant level chamber H in which the fuel is maintained substantially at the level A-A by heat mechanism which has no relation to this invention and which is not shown. The upper end of the passage in is vented to the air inlet passageway by means of The lower end oi the passageway i is provided 3 i with a discharge outlet l9 feeding into the outlet of the carburetor posterior to the throttle valve. This outlet is always subjected to themaximum suction of the engine whenever the throttle valve is in closed or substantially closed position. A regulating screw20 is provided to adjust discharge thru the pasasgeway l 9.

A comparatively large bore 2| is formed in the wall of the carburetor intersecting the passageway l5 substantially at the level of the edge of the throttle valve when it is in closed position. It will be understood that the idle discharge passageways are'formed at thatside of the throttle which moves toward the air inlet during the opening movement thereof, so that more. of the discharge port will be exposed to suction as the throttle is opened. The bore 2| is formed with a. flat bottom so that a. convenient surface .to drill into will be provided.

After forming the flat bottomed bore 2| a pair V of small holes 22 and 23 are drilled from the bottom of the bore 2| into the mixing conduit. The center line 3-3 of these holes may be at an angle to the vertical, as indicated in- Figure 2 so as to give the effect of a single continuous slit, without the necessity of drilling the holes too close together. The hole 22 is formed anterior to the edge of the throttle valve when it is in closed position and is adapted to be swept by the throttle as it moves toward open position.

The hole 23 is preferably formed at the edge of the throttle and in calibrating for a particular engine the exact position and size of this opening may be varied to a certain extent. It may be of slightly greater diameter than the thickness of the throttle valve and over-lap the edge of the throttle slightly on both sides as indicated in Figure 2 but it should be clearly understood that such details will be varied in calibration to fit different types of engines. It will be understood that after forming the openings 22 and 23 a suitable closure such as a plug 25 is provide for the outer end of the bore 2|.

In drilling small holes in cast iron there is no danger of breakage of the metal and the openings are accurately and smoothly formed in production so that when large numbers of carburetors are made there is no substantial variation between the flow curves of carburetors made to the same specification.

I claim:

1. An idle discharge port for carburetors of the type having a butterfly throttle mounted on a transverse shaft in the mixing conduit, comprising a flat bottomed bore drilled into the wall of the mixing conduit, the outer end of said bore being closed, a fuel feeding passage leading into said bore, and two or more small openings leading from the bottom of said bore into the mixing conduit, the axis of said openings lying in a plane which is oblique to the axis of the mixing conduit.

2. An idle discharge port for carburetors of the type having a butterfly throttle mounted on a transverse shaft in the mixing conduit, comprising a flat bottomed bore drilled into the wall of the mixing conduit, the outer end of said bore being closed, a fuel feeding passage leading into said bore, and two or more small openings leading from the bottom of said bore into the mixing conduit, the plane of the center line of said small openings being at an angle to the axis of the mixing conduit, and the openings being formed close together so as to give an effect similar to that of a continuous slit.

3. An idle discharge port for carburetors of the type having a butterfly throttle mounted on a. transverse shaft in the mixing conduit, comprising a bore drilled into the wall of the mixing conduit, the outer end of said bore being closed, a fuel feeding passage intersecting said bore, a pair of small openings leading from the bottom of said bore into the mixing conduit, said openings lying in a plane which is oblique with respect to the axis of the mixing conduit, said fuel feeding passageway extending beyond said bore, and having discharge outlets into the mixing conduit at a point posterior to the throttle, and a regulating screw for said discharge outlet.

4. The combination with a carburetor, of a carbureting passage, a main fuel feed discharging into the passage, a throttle mounted on a transverse shaft in the carbureting passage, an idle discharge port including a bore drilled into the wall of the mixing conduit and extending below said throttle when in its closed position, a plurality of openings leading from said bore into said mixing conduit, said openings being positioned in staggered relation, certain of said openings being formed at a position adjacent the throttle when in its closed position and being arranged in a plane which is oblique in respect to the axis of the mixing conduit, and a regulating screw for one of said openings.

5. The combination with a carburetor, of a carbureting passage, a main fuel feed discharging into the passage, a throttle mounted on a transverse shaft in the carbureting passage, an idle discharge port including a bore drilled into the wall of the mixing conduit and extending below said throttle when in its closed position, a plurality of openings leading from said bore into said mixing conduit, certain of said openings being closely grouped and in a plane which is oblique to the axis of the mixing conduit, one of the openings of said group being of such size and so positioned as to extend beyond the walls of said throttle when the latter is in closed position, and a regulating screw for an opening positioned below said group of openings.

HENRY A. BOLLER. 

